Magnetothermal electrical circuit breaker

Abstract

 A magnetothermal electric circuit breaker, comprising a casing which contains at least two fixed electrical contacts in a parallel arrangement which are separated by an insulating partition, each contact being associated with an arc quenching chamber, an electrical protection component associated with a magnetic tripping mechanism, a mechanism for the actuation of at least two electrical moving contacts in a parallel arrangement, a thermal tripping mechanism, a connection means for the external electrical connections; each one of the electrical moving contacts includes a double contact.

Description

[0001] The present invention relates to a magnetothermal electrical circuit breaker.

[0002] The present invention relates in particular to circuit breakers for high currents, up to 125 A.

[0003] Magnetothermal electrical circuit breakers use mechanisms which allow to open and close the moving contact both by actuating an external lever, which can be accessed by the user, and by means of the automatic tripping of the protection devices provided internally.

[0004] The two constant problems in the design of these circuit breakers are the complexity of the mechanisms and the dimensions.

[0005] The need is constantly felt to simplify the mechanisms from the point of view of construction in order to allow low-cost manufacture, and in this field it is also very important to achieve an assembly which is simple and can be automated.

[0006] Another requirement, from the point of view of the user, is to allow quick and easy installation of the circuit breaker.

[0007] Another fundamental problem is to improve the performance of circuit breakers while maintaining small dimensions and in any case within the standards.

[0008] The aim of the present invention is to provide a magnetothermal electrical circuit breaker having improved electrical characteristics.

[0009] Another object of the present invention is to provide an electrical circuit breaker which can be manufactured more cheaply than conventional ones and at the same time has an improved performance.

[0010] Another object of the present invention is to provide a circuit breaker which is more reliable in use.

[0011] This aim, these objects and others which will become better apparent hereinafter are achieved by a magnetothermal electric circuit breaker comprising a casing which contains at least two fixed electrical contacts in a parallel arrangement and separated by an insulating partition, each contact being associated with an arc quenching chamber, an electrical protection component associated with a magnetic tripping mechanism, a mechanism for the actuation of at least two electrical moving contacts in a parallel arrangement, a thermal tripping mechanism, a connection means for the external electrical connections, characterized in that each of said electrical moving contacts comprises a double contact.

[0012] Further characteristics and advantages of the present invention will become apparent from the following detailed description of preferred but not exclusive embodiments thereof, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

Figure 1 is a side elevation view of the circuit breaker according to the invention, with a wall of the casing removed;

Figure 2 is a partial perspective view of the circuit breaker according to the invention, showing a removable terminal;

Figure 3 is a view, similar to Figure 2, of another type of removable terminal;

Figure 4 is a perspective view of a plurality of circuit breakers according to the invention in the assembled condition;

Figure 5 is a perspective view of the circuit breaker according to the invention, illustrating the contacts in detail;

Figure 6 is an exploded perspective view of the components that constitute the moving contacts;

Figure 7 is a perspective view, taken from the left, of the moving contacts in the position in which the circuit breaker is open;

Figure 8 is a perspective view, taken from the left, of the moving contacts in the position in which the circuit breaker is closed;

Figure 9 is a side elevation view of the moving contacts in the position in which the circuit breaker is closed;

Figure 10 is a bottom perspective view of the moving contacts;

Figure 11 is a side elevation view of the moving contacts in the position in which the circuit breaker is open, showing the abutment component for independent switching;

Figure 12 is a side elevation view of the moving contacts during closure, illustrating the abutment component for independent switching which locks the contacts;

Figure 13 is a side elevation view of the moving contacts in the closed position, illustrating the abutment component for independent switching which releases the contacts;

Figure 14 is a side elevation view of the mechanism of the moving contact in the position in which the circuit breaker is open;

Figure 15 is a side elevation view of the mechanism of the moving contact in the position in which the circuit breaker is closed;

Figure 16 is a side elevation view of the thermal mechanism in the position after tripping;

Figure 17 is a side elevation view of the magnetic tripping mechanism in the position after tripping.

[0013] With reference to the above figures, the magnetothermal circuit breaker according to the invention, generally designated by the reference numeral 100, comprises a casing 101, which has the typical standardized shape, and, at the rear face 102, defines a means 103 for coupling to an omega-shaped guide (not shown) according to DIN standards.

[0014] The casing 101 has, at its front face, a protrusion 104 in which the actuation component, or actuation lug 105, is arranged. The casing 101 contains an electrical protection component 106 which is associated with a magnetic tripping mechanism 107, a mechanism for actuating the electric moving contact 108, a thermal tripping mechanism 109, and electrodes 110 for the external electrical connections.

[0015] As shown in Figures 2 and 3, proximate to each electrode 110, the casing 101 has front panels 111 which slide off upward along guides 112 which are formed in the casing 101, so as to expose the electrodes 110.

[0016] In particular, Figure 2 shows a front panel 111 which has been slid off the casing 101 in order to access an electrode 110 to which it is possible to apply, by means of an Allen screw, a cable terminal 113 for a connecting cable. The front panel 111 allows the cable terminal to exit through a lower opening.

[0017] Figure 3 illustrates a front panel 111 which has been slid off the casing 101 in order to access an electrode 110 to which it is possible to apply a removable terminal 114 which can be directly connected to an end of an electrical cable. In this case, the front panel 111 allows the cable to exit through a lower opening.

[0018] A blade 115 is electrically connected to the electrodes 110 and is adapted to receive a connector 121 of the Faston type through an opening in the front panel 111 for the connection of auxiliary means such as for example voltmeters, luminous indicators, and minimum-voltage relays.

[0019] The circuit breakers can be paired, as shown in Figure 4. Safety insulating partitions 116 separate two adjacent terminals. The partitions are inserted by sliding one side 117, which has a T-shaped profile, in a slot 118 formed in the lateral edge of the front panels 111. There is also a reinforcement bar which has a triangular profile 119 and allows to actuate the lugs so as to simultaneously open and close all the connected circuit breakers. Gas vent channels 120 are provided at the base of the casing and their arrangement is shown in the figures.

[0020] Inside the casing 101, the components of the circuit breaker are provided so as to allow the parallel operation of two fixed contacts 1 on which two moving contacts 2 respectively close. Each of the moving contacts is a double moving contact according to the invention: in particular, as shown in Figure 5, the two fixed contacts, which are identical, are arranged side by side and are connected, as shown in Figure 1, to two independent arc quenching chambers 3 which are separated by an insulating partition 4. A curved transfer electrode 5 is arranged in front of the fixed electrode 1 in order to transfer the arc in case of tripping.

[0021] The two electrical moving contacts 2, according to the invention, are split, as shown in particular in Figures 5, 7, 8 and 10. In particular, splitting is achieved by assembling two individual forks so as to provide a double fork. In detail, there is a first single fork 6 in which the arms 7 and 8 form the moving contacts 2; the fork 6 further includes a tab 9. There is also a second single fork 10, in which the arms 11 and 12 couple respectively to the arms 7 and 8 of the fork 6, providing the double contacts 2. The fork 10 comprises a tab 13, and an arc-like connecting member 14 is provided between the arms 11 and 12.

[0022] On assembly of the two forks, the arc-like connecting member 14 of the second fork 10 is arranged so that the arm 11 lies inside the arm 7 while the arm 12 lies outside the arm 8. The tab 13 of the fork 10 lies exactly to the side of the tab 9 of the form 6. The two forks 6 and 10 are sized so as to have a single profile laterally, as shown in Figure 9, particularly with two fully symmetrical split contacts 2. The two forks 6 and 10 are fixed to a locking member 15 by means of an actuation pivot 16 which enters slots 17, formed in the tabs 9 and 13 of the forks 6 and 10, and holes 18, formed in the locking member 15. The locking member 15 is pivoted, by means of holes 19, to a guiding pivot 20 which is rigidly coupled to the casing 101, around which it can rotate together with the forks 6 and 10. Each of two actuation springs 21 is coupled at one end to a hollow 22, provided in the tabs 9 and 13 of the forks 6 and 10, and, at the other end, to a per se known thermal tripping adjustment support 23, associated with the casing 101, as shown in Figure 9. During the rotation that produces the closure of the contacts, the actuation springs 21 are loaded, as described in detail hereinafter. If one of the two double contacts 2 wears abnormally with respect to the other, the forks 6 and 10 in any case ensure contact, since they can oscillate about the pivot 16 by virtue of the play provided by the slots 17. The actuation springs 21 are also adapted to compensate for this play, thus rendering the forks 6 and 10 self-centering.

[0023] The forks 6 and 10, the locking member 15 and the actuation springs 21 are an integral part of the mechanism for actuating the electrical moving contact.

[0024] Switching for closing the circuit breaker occurs as follows.

[0025] Starting from the position in which the circuit breaker is open, as shown in Figure 14, the lug 105 is actuated and the lug crossbar 24 descends, producing the clockwise rotation of an engagement lever 25 about the pivot 16. During the rotation, a wedge 26 provided on the contour of the profile of the engagement lever 25 abuts against a step-like recess 27 which is provided on a protruding surface 28 of a disengagement lever 29 which is in turn pivoted in the pivot 20, stopping its rotation. At this point, the engagement lever 25 and the disengagement lever 29 form a rigidly coupled member which, under the action of the lug crossbar 24, turns counterclockwise about the pivot 20, moving the forks 6 and 10, so as move the moving contacts 2 closer to the fixed contacts 1, tensioning the actuation springs 21. As the rotation continues, at a certain distance from the fixed contacts 1, for example one millimeter, the further descent of the forks 6 and 10 is rendered independent of the motion of the lug 105 by means of an abutment component 30 which engages between a rear tab 31 of the locking member 15 and the front of the hollow 22 of the forks 6 and 10, as shown in succession in Figures 11 and 12. In this manner, the closure of the contacts is halted until the contact plate 32 provided on the abutment member 30 trips and allows to instantaneously release the force applied by the lug crossbar 24, closing the contacts with constant pressure, as shown in Figure 13.

[0026] In Figure 15, the circuit breaker is shown in the position in which the contact is closed; in this position, the moving contact 2 rests on the fixed contact 1. In particular, the disengagement lever 29 ends its rotation by approaching, with its protrusion 33, an arm 34 of a motion lever 35. The actuation springs 21 cannot be released by opening the contacts, since the position of the lug crossbar 24, by using as a lever the lug 105 that has reached the end of its stroke, prevents the clockwise rotation of the forks 6 and 10.

[0027] In order to open the circuit breaker it is sufficient to operate the lug 105 in the opposite direction enough to allow immediate opening of the contacts under the action of the actuation springs 21, which are released.

[0028] Emergency thermal tripping occurs as follows with reference to Figures 14 and 15.

[0029] A bimetallic member 36 moves toward the inside of the circuit breaker, moving with it a thermal linkage 37 which makes contact with an inclined plane 59 of the disengagement lever 29, causing its clockwise rotation about a center 20, kept in position by the casing 101. The rotation allows the wedge 26 of the engagement lever 25 to move beyond the step-like recess 27 of the disengagement lever 29 and to slide along the protruding surface 28, thus causing the mutual uncoupling of the engagement lever 25 and the disengagement lever 29. Without the contrasting reaction of the lug crossbar 24, which now acts exclusively on the engagement lever, the action of the actuation springs 21 cannot be contrasted, and accordingly the contacts open with a snap action. At the same time, the engagement lever 25, which is no longer contrasted, turns clockwise, striking a tab 39 of the motion lever 35 so as to accelerate its motion. This is necessary because the motion lever 35 is provided with a hole which can be engaged by a pivot for the operational connection of a separate electrical module, allowing the cascade tripping of the module or modules associated with the circuit breaker.

[0030] The disengagement lever 29 is returned to its position by a contact spring 40. Also, the motion lever 35 is returned to the position that it had prior to tripping by a double spring 60.

[0031] The initial position of the thermal linkage 37 can be adjusted by means of the thermal unit adjustment screw 41 which, by acting on the thermal unit adjustment support 23, by means of a threaded plate 42, can raise or lower the thermal linkage 37, which moves toward or away from the inclined plane 61 of the bimetallic component 36. It is thus possible to obtain an effective preliminary positioning of the thermal linkage 37.

[0032] From the closed position, shown in Figure 14, in case of magnetic tripping, a magnetic pusher 43, actuated by the electrical protection member 106, moves upward, pushing a lower portion of the disengagement lever 29. The consequent clockwise rotation of the disengagement lever 29 causes the uncoupling of the engagement lever 25, as described in the preceding paragraph, thus activating the previously described disengagement sequence. Moreover, during rotation, the disengagement lever 29 strikes, with its end 44, the lower part of the moving contacts 2, accelerating their opening, as shown in Figure 16. The magnetic pusher 43 is repositioned by means of a magnetic spring which is released during tripping and is present in the electrical protection component.

[0033] The circuit breaker according to the invention further includes a device for signaling the position of the moving contact 45.

[0034] The circuit breaker, according to the invention, has two moving contacts arranged in parallel which are actuated by means of the same mechanism; each moving contact is capable of closing the circuit independently of the other on the two fixed contacts, each of which is connected to an arc quenching chamber.

[0035] Another advantage is constituted by the fact that each one of the two moving contacts is a double contact. This solution allows to halve the heating power that is dissipated when the contacts close. A split moving contact in fact closes on each fixed contact, and therefore each one of the two contact surfaces is crossed by half the current with respect to a single moving contact; as a result, the dissipated power is reduced to one quarter, and since the contact is split, the total dissipated power is half that of a single double moving contact.

[0036] With this solution, it is no longer necessary to apply silver pads to the moving contact, limiting exclusively to the fixed contact the delicate operations linked to pad welding.

[0037] Another advantage consists of the possibility to extract the terminals, allowing to connect the cables to the electrodes more rapidly and easily.

[0038] In practice it has been observed that the invention achieves the intended aim and objects.

[0039] The circuit breaker according to the invention is susceptible of numerous modifications and variations, within the scope of the appended claims. All the details may be replaced with technically equivalent elements.

[0040] The materials used, as well as the dimensions, may of course be any according to requirements and to the state of the art.

Claims

1. A magnetothermal electric circuit breaker comprising a casing which contains at least two fixed electrical contacts in a parallel arrangement which are separated by an insulating partition, each contact being associated with an arc quenching chamber, an electrical protection component associated with a magnetic tripping mechanism, a mechanism for the actuation of at least two electrical moving contacts in a parallel arrangement, a thermal tripping mechanism, a connection means for the external electrical connections, characterized in that each electrical moving contact comprises a double contact.

2. The magnetothermal electric circuit breaker according to claim 1, characterized in that said electric moving contacts comprise a first single fork and a second single fork which are coupled so as to provide two moving contacts.

3. The magnetothermal electric circuit breaker according to claim 1 or 2, characterized in that said first single fork comprises a first arm, a second arm and a rear tab and said second single fork comprises a first arm, a second arm, a rear tab and a curved connecting member between said first and second arms.

4. The magnetothermal electric circuit breaker according to one or more of the preceding claims, characterized in that said curved connecting member of said second fork is arranged so that said first arm of said second fork lies inside said first arm of said first fork, while said second arm of said second fork lies outside said second arm of said first fork.

5. The magnetothermal electric circuit breaker according to one or more of the preceding claims, characterized in that said arms and said tabs are exactly laterally adjacent and have a single lateral profile,

6. The magnetothermal electric circuit breaker according to one or more of the preceding claims, characterized in that said two forks are coupled to a locking member by means of a motion pivot which enters guiding slots formed in said tabs of said forks and holes formed in said locking member, said locking member being pivoted by means of holes to a guiding pivot which is rigidly coupled to the casing and around which it can rotate together with said forks.

7. The magnetothermal electric circuit breaker according to one or more of the preceding claims, characterized in that it comprises two actuation springs, each of which is engaged, at one end, to a hollow formed in said tabs of said forks and, at the other end, to a thermal unit adjustment support which is associated with said casing.

8. The magnetothermal electric circuit breaker according to one or more of the preceding claims, characterized in that said forks are self-centering, since they can oscillate about said motion pivot because of the play provided by said guiding slots of said tabs.

9. The magnetothermal electric circuit breaker according to one or more of the preceding claims, characterized in that, starting from the open position, if said lug is actuated, said lug crossbar descends and causes the clockwise rotation of an engagement lever about said motion pivot; during said rotation, a wedge provided on the contour of the profile of said engagement lever abuts against a step-like recess which is provided on a protruding surface of a disengagement lever which is pivoted on said guiding pivot, stopping its rotation, said engagement lever and said disengagement lever forming a monolithic member which, under the action of said lug crossbar, turns counterclockwise about said guiding pivot, moving said forks, causing the approach of said moving contacts to said fixed contacts, and tensioning said actuation springs; at a preset distance from said fixed contacts, the further descent of said forks is rendered independent of the motion of said lug by means of an abutment member which engages between a rear tab of said locking member and the front of said hollow of said forks, stopping the closure of said contacts until a contact plate, provided on said abutment member, trips and allows to instantly discharge the force applied, closing the contacts with constant pressure.

10. The magnetothermal electric circuit breaker according to one or more of the preceding claims, characterized in that in the position in which the contact is closed said disengagement lever ends its rotation by approaching, with a protrusion with which it is provided, an arm of a motion lever; said actuation springs being unable to release upon opening said contacts, since the position of said lug crossbar, by using said lug as a lever, at the end of its stroke, prevents the clockwise rotation of said forks.

11. The magnetothermal electric circuit breaker according to one or more of the preceding claims, characterized in that in order to open said circuit breaker it is sufficient to actuate said lug in the opposite direction, said lug crossbar being arranged so as to allow the immediate opening of said contacts under the action of said actuation springs, which are released.

12. The magnetothermal electric circuit breaker according to one or more of the preceding claims, characterized in that during emergency thermal tripping a bimetallic component moves and draws with it a thermal linkage which makes contact with an inclined plane of said disengagement lever, causing its clockwise rotation about a center which is kept in position by said casing, said rotation allowing said wedge of said engagement lever to move beyond said step-like recess of said disengagement lever and to slide along said protruding surface, thus causing the mutual disengagement of said engagement lever and said disengagement lever, said lug crossbar acting exclusively on the engagement lever, allowing said actuation springs to release, opening said contacts.

13. The magnetothermal electric circuit breaker according to one or more of the preceding claims, characterized in that during said thermal tripping said engagement lever, no longer contrasted, turns clockwise, striking against a tab of said motion lever, accelerating its motion.

14. The magnetothermal electric circuit breaker according to one or more of the preceding claims, characterized in that said disengagement lever and said motion lever are returned to the initial position by a contact spring and by a double spring.

15. The magnetothermal electric circuit breaker according to one or more of the preceding claims, characterized in that in the position in which the circuit breaker is closed, in case of magnetic tripping, a magnetic pusher moves upward, pushing a lower portion of said disengagement lever, causing said mutual disengagement of said engagement lever and said disengagement lever, allowing said actuation springs to release, opening said contacts, said disengagement lever striking, with one of its ends, the lower part of said moving contacts, accelerating their opening, said magnetic pusher being returned to the initial position by means of a magnetic spring which is released during tripping.

16. The magnetothermal electric circuit breaker according to claim 1, characterized in that it comprises a removable electrode which can be reached by removing a front panel along guides formed in said casing proximate to said electrode, said electrode being adapted to be connected to a cable terminal of an electrical cable, which can be detachably applied to the electrode for the external electrical connections of said circuit breaker.

17. The magnetothermal electric circuit breaker according to claim 1, characterized in that it comprises a terminal for an electrical cable which can be detachably applied to an electrode for the external electrical connections of said circuit breaker, said electrode being accessible by removing a front panel along guides formed in said casing proximate to said electrode.

Drawing